The invention relates to a heat exchanger comprising at least one manifold the internal volume of which is defined by at least one longitudinal bore formed in an elongate solid body, and is in fluid communication with a row of tubes which are mutually aligned in the axial direction of the bore or bores, elongate parallel to one another in a first direction substantially perpendicular to the said axial direction and having an elongate cross section in a second direction substantially perpendicular to the axial direction and substantially perpendicular to the said first direction.
Such heat exchangers are used especially for extracting heat from a refrigerant fluid in a motorvehicle air-conditioning installation, and, more particularly, when the refrigerant fluid is one of those which, like CO2, have to be subject to very high pressures, for example of several hundred bar. The manifolds used in the conventional air-conditioning condensers, comprising a tubular wall formed from one or more rolled metal sheets, would not in fact withstand such pressures, and a solid component is required in order to furnish sufficient wall thickness.
However, if the ends of the tubes open out directly into a bore defining the internal volume of the manifold, as they do within the tubular, sheet-metal wall of conventional manifolds, the high wall-thickness of the manifold adds to the space taken up by the tubes in the second direction, correspondingly increasing the overall space required for the heat exchanger.
The object of the invention is to remedy this drawback, and to reduce the overall size of the heat exchanger in the second direction, for a given length of the cross section of the tubes.
The invention especially envisages a heat exchanger of the kind defined in the introduction, and provides for only a part of the length of the cross section of the tubes to project, along the said first direction, into the said internal volume, the leaktightness of the fluid communication between the tubes and the internal volume being obtained by means of a cradle in the form of a profiled strip, accommodating the said body and brazed to it and to the periphery of the tubes.
Optional characteristics of the invention, which are complementary or alternative, are set out below:
at least one end of the length of the cross section of the tubes projects along the said first direction beyond the bore or the set of bores in the second direction;
an intermediate part of the length of the cross section of the tubes projects along the said first direction between two bores defining the said internal volume;
one end of each tube is engaged in a slot formed in the said body, elongate in the second direction, opening out at its two ends and the bottom of which is interrupted by the said internal volume, the said cradle being applied to the body in such a way as to cover over the said slots and exhibiting, opposite them, elongate apertures for the leaktight passage of the tubes;
each slot features two lateral regions of a reduced depth the bottom of which serves as an abutment for the end of the tube and a deeper central region defining a free space which communicates with the inside of the tube;
one end of each tube is engaged so as to be leaktight to the fluid in a stamped cup of the cradle, the bottom of which is itself housed in a leaktight way in a transverse notch of the body and traversed by at least one aperture for fluid communication between the tube and the said internal volume;
the body and the cradle feature means for mutual mechanical fastening;
the said fastening means comprise two step features extending in the axial direction on the outer surface of the body, respectively on either side of a plane passing through the axes of the tubes, and interacting with teeth of the cradle;
each tooth is formed at the free end of a lug extending substantially in a radial plane, each lug being interposed in the axial direction between two cups;
the manifold includes at least one transverse partition delimiting, in the axial direction, at least one chamber which forms part of the said internal volume, engaged in an aperture of the body which is covered over by the cradle;
the manifold includes at least one transverse partition delimiting, in the axial direction, at least one chamber which forms part of the said internal volume, engaged in an aperture of the body beyond which it protrudes and carrying means for mechanical fastening onto the periphery of the body.